Updates in jackson directory

[arh4uwe]

I've made some helpful changes and additions to the Lean files in the jackson directory. These include:

• Fixing typos and errors in concept/collection.lean and concept/trash.lean
• Creating a successful proof that (insert_0 ns) = [0,1,2,3] at the end of collection_and_trash/list_collection_test.lean
• Creating a Lean implementation of the "contributing factor" concept in mod/contributing_factor.lean
• Creating a Lean implementation of the "mod report" concept in mod/mod_report.lean
• Creating tests of the two above implementations in mod/test.lean

[kevinsullivan]

Good work, Amanda.